Ratchet wrench

ABSTRACT

An electric ratchet wrench as one example of the ratchet wrench includes an electric motor, a holder that rotatably holds a socket via a one-way clutch mechanism, and a spindle configured to convert a driving force from the motor into a reciprocating rotation motion of the holder. A space is provided between the socket and the holder. The space includes large interval portions and small interval portions. The small interval portions are adjacent to the large interval portions in a rotation direction (lock direction) of the socket and have distances smaller than distances of the large interval portions. Additionally, the one-way clutch mechanism includes columnar locking pins disposed between the spaces and have a diameter with a size equal to or less than the distances of the large interval portions and exceeding the distances of the small interval portions.

This application claims the benefits of International Application No.PCT/JP2018/027748, filed on Jul. 24, 2018, which claims the benefit ofJapanese Patent Application No. 2017-150941, filed on Aug. 3, 2017, theentirety of which is incorporated by reference.

BACKGROUND OF INVENTION Technical Field

The invention relates to an electric or air-driven ratchet wrench.

Background Art

There has been known an electric ratchet wrench, which is also usedmanually, used to, for example, fasten a nut and a bolt as described inJapanese Laid Open Patent Publication No. 7-124871.

In the electric ratchet wrench, upper and lower end portions of acylindrical socket rotatably supported to a distal end of a housing in astate where the socket is exposed on both upper and lower sides are heldto a ratchet holder performing a reciprocating rotation operation. Thesocket has an outer peripheral surface where a sawtooth surface formedby arranging a ridge group having a mountain shape in cross section inparallel across the whole circumference is formed. Further, a ratchetclaw that meshes with the sawtooth surface on the socket so as to allowa rotation in a free direction and restrict a rotation in a lockdirection, which is a direction opposite to the free direction, isdisposed outside the socket.

In the electric ratchet wrench, the reciprocating rotation operation bythe ratchet holder in a state where the nut or the like is inserted intoan upper half portion or a lower half portion of the socket progressesthe fastening of the nut or the like via the socket. The action of theratchet claw to the sawtooth surface intermittently progresses thefastening of the nut or the like in the lock direction each time theratchet holder performs the reciprocating rotation operation, and thesocket idles to the ratchet holder in the free direction.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

With the above-described electric ratchet wrench, the meshing of theratchet claw with the sawtooth surface on the socket achieves the lockdirection and the free direction. Therefore, to improve strength of thelock, the ratchet claw and the sawtooth need to be increased in size,and there is a limit on achieving both compactability and a performance,such as the strength of lock and reliability of the operation.

Additionally, with the above-described electric ratchet wrench, the freedirection and the lock direction are fixed. Accordingly, to switch thesedirections to the opposite directions substantially, it is necessary toreverse the electric ratchet wrench with respect to the nut or the liketo change the insertion of the nut or the like from the inside of thelower half portion to the inside of the upper half portion of the socketor vice versa, requiring a lot of labor.

Additionally, with the above-described electric ratchet wrench, in acase where the nut or the like can be inserted only from the lower sidedue to, for example, a member being disposed on the upper side of thesocket, the free direction and the lock direction cannot be switched tothe opposite directions.

The main object of the invention is to provide a ratchet wrenchachieving both compactability and a lock performance.

Additionally, the main object of the invention is to provide the ratchetwrench having further better operability regarding switching of a lockdirection.

Further, the main object of the invention is to provide the ratchetwrench that performs the switching of the lock direction with morecertainty.

Solutions to the Problems

An invention according to first aspect is a ratchet wrench that includesan electric or air-driven motor, a holder, and reciprocating motionconversion mechanism. The holder rotatably holds a tool bit or a toolbit holder via a one-way clutch mechanism. The reciprocating motionconversion mechanism is configured to convert a driving force from themotor into a reciprocating rotation motion of the holder. A space isprovided between the tool bit or the tool bit holder and the holder. Thespace includes large interval portions and small interval portions. Thesmall interval portions are adjacent to the large interval portions in arotation direction of the tool bit or the tool bit holder. The smallinterval portions have distances smaller than distances of the largeinterval portions. The one-way clutch mechanism includes locking membersdisposed in the space. The locking member has a size equal to or lessthan the distance of the large interval portion and exceeding thedistance of the small interval portion.

An invention according to second aspect, which is in the above-describedinvention, the locking member may include a pair of planar portions anda pair of bulge portions. The pair of planar portions may be arranged ina direction that the small interval portion is disposed viewed from thelarge interval portion. The pair of bulge portions may couple betweenend portions of the planar portions. A size between the pair of bulgeportions may be equal to or less than the distance of the large intervalportion and exceeding the distance of the small interval portion.

An invention according to third aspect, which is in the above-describedinvention, the pair of the planar portions may be parallel to oneanother.

An invention according to fourth aspect which is in the above-describedinvention, the pair of planar portions may have a posture of expandingtoward the tool bit or the tool bit holder.

An invention according to fifth aspect, which is in the above-describedinvention, the locking member may be at least one ball.

An invention according to sixth aspect is a ratchet wrench that includesan electric or air-driven motor, a holder, and reciprocating motionconversion mechanism. The holder rotatably holds a tool bit or a toolbit holder via a one-way clutch mechanism. The reciprocating motionconversion mechanism is configured to convert a driving force from themotor into a reciprocating rotation motion of the holder. A space isprovided between the tool bit or the tool bit holder and the holder. Thespace includes large interval portions and small interval portions. Thesmall interval portions are adjacent to the large interval portions in arotation direction of the tool bit or the tool bit holder. The smallinterval portions have distances smaller than distances of the largeinterval portions. The one-way clutch mechanism includes columnar orcylindrical locking members disposed in the space. The locking memberhas a diameter having a size equal to or less than the distance of thelarge interval portion and exceeding the distance of the small intervalportion.

In an invention according to seventh aspect, which is in theabove-described invention, the small interval portions may be disposedon both sides of the large interval portion. A retainer may be disposedbetween the tool bit or the tool bit holder and the holder. The retainermay be configured to change the spaces of the one small interval portionand the large interval portion to the spaces of another of the smallinterval portion and the large interval portion.

An invention according to eighth aspect, which is in the above-describedinvention, the retainer may include a protrusion. A direction switchinglever including a cam portion in contact with the protrusion may bedisposed on one of the holder and the tool bit or the tool bit holder.

An invention according to ninth aspect, which is in the above-describedinvention, in the retainer, springs that bias the locking member in adirection where the small interval portions are disposed viewed from thelarge interval portions may be disposed.

In an invention according to tenth aspect, which is in theabove-described invention, a plurality of the spaces may be disposed ina state where arrangements of the small interval portions relative tothe large interval portions in the rotation direction are similar to oneanother. The locking members may be disposed in the respective spaces.

In an invention according to eleventh aspect which is in theabove-described invention, the tool bit or the tool bit holder may havean outer surface formed into a side surface shape of a regular polygonalprism. The holder may have an inner surface formed into a cylindricalsurface shape.

Effects of the Invention

The main effect of the invention is to provide a ratchet wrenchachieving both compactability and a lock performance.

Additionally, the main effect of the invention is to provide the ratchetwrench having further better operability regarding switching of a lockdirection.

Further, the main effect of the invention is to provide the ratchetwrench that performs the switching of the lock direction with morecertainty.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an electric ratchet wrench according toa first embodiment of the invention from an upper rear.

FIG. 2 is a right side view of FIG. 1.

FIG. 3 is a center vertical cross-sectional view of FIG. 1.

FIG. 4 is a partial enlarged view of FIG. 3.

FIG. 5 is a top view of FIG. 1.

FIG. 6 is a perspective view of a one-way clutch mechanism of FIG. 1 andits peripheral area.

FIG. 7 is an exploded perspective view of FIG. 6 and its peripheral areaviewed from a left lower side.

FIG. 8 is an exploded perspective view of FIG. 6 and its peripheral areaviewed from a left upper side.

FIG. 9 is a cross-sectional view taken along the line A-A of FIG. 2.

FIG. 10A is an enlarged view of a front right portion of FIG. 9 and adrawing when an operating unit of a direction switching lever is on aright side.

FIG. 10B is an enlarged view of a front right portion of FIG. 9 and adrawing when an operating unit of a direction switching lever is on aleft side.

FIG. 11 is a cross-sectional view taken along the line B-B of FIG. 5.

FIG. 12 is a cross-sectional view taken along the line C-C of FIG. 3.

FIG. 13A is an enlarged view of a front portion of FIG. 12 and a drawingwhen the operating unit of the direction switching lever is on a rightside.

FIG. 13B is an enlarged view of a front right portion of FIG. 12 and adrawing when an operating unit of a direction switching lever is on aleft side.

FIG. 14A is an enlarged view similar to FIG. 10A and a drawing when anoperating unit of a direction switching lever is on a right sideaccording to a second embodiment of the invention.

FIG. 14B is an enlarged view similar to FIG. 10B and a drawing when anoperating unit of a direction switching lever is on a left sideaccording to a second embodiment of the invention.

FIG. 15A is an enlarged view similar to FIG. 10A and a drawing when anoperating unit of a direction switching lever is on a right sideaccording to a third embodiment of the invention.

FIG. 15B is an enlarged view similar to FIG. 10B and a drawing when anoperating unit of a direction switching lever is on a left sideaccording to a third embodiment of the invention.

FIG. 16A is an exploded perspective view of a retainer and balls of anelectric ratchet wrench according to a fourth embodiment of theinvention when viewed from a left upper side.

FIG. 16B is an exploded perspective view of a retainer and balls of anelectric ratchet wrench according to a fourth embodiment of theinvention when viewed from a left lower side.

DESCRIPTION OF PREFERRED EMBODIMENTS

The following describes embodiments of the invention and theirmodification examples based on the drawings as necessary.

Front and rear, up and down, and right and left in the embodiments andthe modification examples are defined for a convenience of explanationand may change according to a situation of a work, a state of a movingmember, and the like.

It should be noted that the invention is not limited to the followingembodiments and modification examples.

First Embodiment

FIG. 1 is an example of a straight type electric power tool and aperspective view of an electric ratchet wrench 1 according to the firstembodiment of the invention, which is an example of a ratchet wrench, ina battery separated state from an upper rear. FIG. 2 is a right sideview of the electric ratchet wrench 1 in a battery mounted state (thesame applies to the following). FIG. 3 is a center verticalcross-sectional view (a battery 10, a controller 61, a switch 62, and amotor 16 are not in cross section) of the electric ratchet wrench 1.FIG. 4 is a partial enlarged view of FIG. 3.

The electric ratchet wrench 1 includes a housing 2 forming its casing.

The electric ratchet wrench 1 includes, in an order from a rear side toa front side, a battery mounting portion 12 to which the battery 10 ismounted, a handle portion 14 gripped by a user, a power unit 18including the motor 16, a power transmission unit 24 including aplanetary gear mechanism 20 and a spindle 22, and an output unit 32including a holder 26 and a socket 28 and a one-way clutch mechanism 30interposed between the holder 26 and the socket 28.

In the electric ratchet wrench 1, these main components (especially themotor 16, the planetary gear mechanism 20, and the spindle 22) arelinearly arranged, serving as an electric power tool (straight typeelectric power tool) having one rod shape or an “I” shape as a whole.

The motor 16 is a driving source of the electric ratchet wrench 1. Arotation of the motor 16 is transmitted to the holder 26 in a statewhere deceleration and reciprocating motion conversion are performed bythe planetary gear mechanism 20 and the spindle 22 as a powertransmission mechanism, and the socket 28 as a tool bit holder slides toidle relative to the rotation of the holder 26 in a predetermineddirection (free direction) via the one-way clutch mechanism 30. Arotation of the holder 26 in a lock direction, a direction opposite tothe free direction, is output so as to lock and rotate together with thesocket 28.

To the socket 28, a socket adapter 34 as a tool bit is mountable in astate where a direction of its center axis (output axis O) is in anup-down direction. The socket adapter 34 includes a hexagonal nut-shapedjoint portion 34 a, a flange portion 34 b on a lower side of the jointportion 34 a, and a quadrilateral driving portion 34 c on a lower sideof the flange portion 34 b. The joint portion 34 a is put into thesocket 28. Various kinds of exchange sockets (not illustrated) aremounted to the quadrilateral driving portion 34 c, which protrudesdownward from the socket 28, and insertion of a bolt and a nut into theexchange socket, for example, fastens these components. The output axisO as a center axis from an upper end through a lower end of the socketadapter 34 or its extended line is in a direction (up-down direction)intersecting with a machine axis M in a front-rear direction as a centeraxis of the main components (especially the motor 16, the planetary gearmechanism 20, and the spindle 22) or its extended line, and protrudesdownward in the quadrilateral driving portion 34 c. Here, the machineaxis M (or its extended line) and the output axis O (or its extendedline) are orthogonal to one another.

Since the direction of the machine axis M intersects with the directionof the output axis O, the electric ratchet wrench 1 is a kind of anangle electric power tool. It should be noted that the exchange socketmay be handled as the tool bit, and the socket adapter 34 may be handledas the tool bit holder.

The housing 2 includes a main body housing 40 and a gear housing 42. Themain body housing 40 serves as a casing of the battery mounting portion12, the handle portion 14, the power unit 18, and a rear half portion ofthe power transmission unit 24, and the gear housing 42 serves as acasing of the power transmission unit 24 and the output unit 32.

It should be noted that the arrangement of various kinds of members inthe various kinds of housings and cases appropriately includes a casewhere a part of the member is in the housing and the case and theremaining part projects or is exposed from the housing and the case, inaddition to a case where the members are completely in the housing andthe case. Additionally, such an arrangement appropriately includes acase where the members are indirectly supported, in addition to a casewhere the members are directly supported to the housing and the case.

The main body housing 40 is laterally halved and includes a left mainbody housing 44 and a right main body housing 45. The left main bodyhousing 44 includes a plurality of screw boss portions 46, and the rightmain body housing 45 includes screw-holes corresponding to therespective screw boss portions 46. The left main body housing 44 and theright main body housing 45 are mated with a plurality of screws 48 eachinserted into the pair of the screw-hole and the screw boss portion 46.

The gear housing 42 is a loupe-shaped member made of metal. Ahandle-shaped portion 50 at the rear of the loupe-shaped portion has acylindrical shape and has a front diameter-expanded portion having anexpanded diameter and a rear diameter-expanded portion having a furtherexpanded diameter at its rear portion. Additionally, a frame-shapedportion 52 at a front portion of the loupe-shaped portion has a forkedshape that projects from the front portion of the handle-shaped portion50 to expand forward like a trumpet shape and further each projectforward from the top and the bottom, and each projection has a roundedframe.

The handle-shaped portion 50 has a rear portion interposed into a frontend portion of the main body housing 40, and thus the gear housing 42 iscoupled to the main body housing 40. The diameter-expanded portions(especially the rear diameter-expanded portion) of the handle-shapedportion 50 avoid the gear housing 42 to come off forward.

The battery 10 is a 10.8V (bolt) lithium-ion battery that contains eightcells as rechargeable cells (not illustrated) in a rectangularparallelepiped-shaped battery case made of resin. The cell has acolumnar shape long in an axis direction and directed in a longitudinaldirection of the battery case. The battery 10 is rechargeable, and theelectric ratchet wrench 1 is a rechargeable ratchet wrench.

The battery 10 has a plurality of groove portions (not illustrated)extending in the longitudinal direction formed on one surface (widesurface) of the battery case. In each groove portion, a battery terminalelectrically coupled to the cell is disposed to be exposed in the grooveportion. It should be noted that the battery terminal is not limited tobe installed in the groove portion and, for example, may project or bebiased during mounting.

Additionally, a microcomputer (not illustrated) is built into thebattery 10. The microcomputer controls an operation of the battery 10,such as a supply of electric power from the cell to the batteryterminal.

Groove-shaped rail guides 54 having a longitudinal direction in thefront-rear direction are disposed on right and left of the battery caseof the battery 10 when the battery terminals are faced downward.

Additionally, the battery 10 includes a battery claw 55 configured toproject in a state of being biased from an installation surface in aprojection direction on a side edge of the installation surface of thebattery terminals. The battery claw 55 is integrated with a batterylever (not illustrated) disposed on a surface adjacent to theinstallation surface of the battery terminals and a surface close to thebattery claw 55. An operation of the battery lever allows the batteryclaw 55 to sink into the battery case against a biasing force.

Further, the battery 10 includes a battery state display unit 56 and abutton (not illustrated). The battery state display unit 56 displays astate of the battery 10, such as an amount of charge (remainingcapacity) of the battery 10, on a surface on a side opposite to thebattery lever. The battery state display unit 56 includes a plurality of(four) lamps (not illustrated) arranged in the longitudinal direction onthe installation surface. When the button is pressed, the microcomputerlights up the lamps by the number according to the current remainingcapacity in the battery state display unit 56 from one end side for apredetermined period. Additionally, when the remaining capacity is equalto or less than a predetermined threshold and therefore the charging isrequired, the microcomputer flashes one lamp on the one end side of thebattery state display unit 56 for a predetermined period. Further, whenthe battery 10 has a failure, such as a current value between the celland the battery terminal in excess of a predetermined threshold, themicrocomputer flashes two lamps on one end side and two lamps on theother end side in alternation.

It should be noted that the battery state display unit 56 is variouslychangeable. The battery state display unit 56 may be a seven-segmenttype display unit, the button may be omitted and the display may beperformed, for example, while the battery 10 is mounted, at least one ofthe flash display for charging and the failure display may be omitted,the display may be continued until the button is pressed again or asecond button disposed separately is pressed, another state of thebattery may be displayed, or the battery state display unit 56 may beentirely omitted.

At least any of the installation position of the battery terminal, theinstallation position of the battery lever, and the installationposition of the battery state display unit 56 is variously changeable.For example, the battery lever and the battery state display unit 56 areeach disposed on an identical surface so as not to be disposed onopposed surfaces.

The battery mounting portion 12 is formed at the rear portion of themain body housing 40 and has a flat plate portion expanding into a flatplate shape from front to back and from side to side. The flat plateportion of the battery mounting portion 12 has a depressed portiondepressed downward from its top surface. The flat plate portion, whichoccupies the most part of the battery mounting portion 12, is put to oneside, which is the lower side, with respect to the above-describedextended line of the machine axis M, and the battery mounting portion 12has a front end portion having a staged surface N expanding from side toside and up and down (in further detail, obliquely upward to the front).

The battery mounting portion 12 includes rail portions 57 in thefront-rear direction disposed right and left of the upper portion of thedepressed portion, a plurality of terminals 58 projecting upward from abottom surface of the depressed portion and extending in the front-reardirection, and a hollow 60 formed to be further depressed downward atthe rear portion of the depressed portion. It should be noted that thedepressed portion of the battery mounting portion 12 may be disposed ata part other than one surface of the flat plate portion, such as a topsurface of a semicolumnar portion having a flat top surface and a curvedlower surface.

The controller 61 is disposed below the terminals 58 in the batterymounting portion 12. The controller 61 is held by front and rear ribsformed on an inner surface of the main body housing 40. The respectiveterminals 58 and the controller 61 are electrically coupled to oneanother with a lead wire (not illustrated).

The battery 10 is slid forward from the rear of the battery mountingportion 12 in a state where the battery lever is on the rear side andthe installation surface of the battery terminals are on the lower side,thus being mounted to the battery mounting portion 12.

At this time, the rail portions 57 in the battery mounting portion 12enter the rail guides 54 on the battery 10 to guide the battery 10. Itshould be noted that rail portions may be disposed in the battery 10 andrail guides may be disposed in the battery mounting portion 12, or railportions and rail guides may be omitted.

The corresponding terminals 58 enter the respective groove portions onthe battery 10, and at the completion of mounting, the battery terminalsinside the groove portions contact the terminals 58.

Further, the battery claw 55 of the battery 10 enters the hollow 60 atthe completion of mounting, and thus the battery 10 is reliably held inthe battery mounting portion 12. Additionally, when the user operatesthe battery lever to retreat the battery claw 55 from the hollow 60, thebattery 10 is removable from the battery mounting portion 12 by slidingto the rear.

In addition, a clearance is generated between the battery state displayunit 56 on the front surface of the battery 10 and the staged surface Nof the battery mounting portion 12. Accordingly, the button on thebattery state display unit 56 is easily operated and the display in thebattery state display unit 56 is easily seen. Additionally, by grippingthe front portion of the battery 10, the battery 10 is easily removedfrom the battery mounting portion 12.

The switch 62 is disposed on the handle portion 14.

The switch 62 includes a switch main body 64 and a plunger 66 thatprojects downward from the switch main body 64 in a state whose amountof projection is changeable.

While an external force does not act, the plunger 66 is biased downwardso as to be a predetermined maximum amount of projection, and whenreceiving the action, the plunger 66 moves upward to reduce the amountof projection.

The switch main body 64 changes a switching state according to theamount of projection of the plunger 66. Here, when the amount ofprojection decreases from the maximum amount of projection by apredetermined amount or more and the plunger 66 moves upward from thepredetermined switching position, the switch main body 64 (switch 62)switches on from off, and the switch 62 switches off from on in thereverse situation.

The switch 62 is electrically coupled to the controller 61 via a leadwire (not illustrated).

A paddle-shaped lever 68 is disposed below the switch 62.

The lever 68 includes an arm portion 70 and a bus tab-shaped buttonportion 72 bulging downward.

Pins are stood on right and left of a rear end portion of the armportion 70 so as to project outward in the right-left direction, andsupporting the arm portion 70 by the main body housing 40 allows thelever 68 to rotate around the pins. Supporting the lower surface of thearm portion 70 to the inner surface of the main body housing 40 sets thelever 68 at a lowest position. The plunger 66 contacts the top surfaceof the rear portion of the button portion 72. At the center of thebutton portion 72, a rib 74 projecting upward is integrally formed. Thebutton portion 72 is exposed in the lower portion of the main bodyhousing 40.

A lock arm 76 is disposed in front of the switch 62 and at the rear ofthe motor 16.

The lock arm 76 is a member extending up and down. Pins are stood onright and left of the center of the lock arm 76 so as to project outwardin the right-left direction. Entering the pins into the cylindricalbosses formed in the inner surface of the main body housing 40 allowsthe lock arm 76 to rotate around the pins.

On an upper end portion of the lock arm 76, a slider 78 having a smallprotrusion shape is disposed to project upward. The slider 78 is exposedfrom a hole 80, which is provided in an upper portion of the main bodyhousing 40.

The lock arm 76 has a lower end portion formed as an arrowhead-shapedportion 82 having an arrowhead shape.

When the user operates the slider 78 to be positioned forward, the lockarm 76 has an inclined posture downward to the rear, and a lower endportion of the arrowhead-shaped portion 82 is adjacent to the upper endportion of the rib 74 of the lever 68. In this state, even when thebutton portion 72 of the lever 68 is pressed upward, the rib 74 abuts onthe arrowhead-shaped portion 82 to hold back upward movements of thebutton portion 72 and the plunger 66 and to block the switching of theswitch 62 to the on-state (off-lock state). A rib 84 in contact with theupper end portion of the arrowhead-shaped portion 82 in the off-lockstate is disposed to project inward from the inner surface of the mainbody housing 40 on the upper side of the arrowhead-shaped portion 82.The rib 84 holds back the upward movement of the arrowhead-shapedportion 82 to reliably block the upward movements of the button portion72 and the plunger 66.

Meanwhile, when the slider 78 is operated to be positioned rearward, thelock arm 76 has an approximately perpendicular posture and thearrowhead-shaped portion 82 is away from a space immediately above therib 74 of the lever 68 and the rib 84. Pressing the button portion 72 ofthe lever 68 in this state rotatably moves the lever 68 upward, theplunger 66 is pressed, and the switch 62 is switched to the on-state(off-lock released state).

Since only the switch 62 and the lock arm 76 are disposed inside thehandle portion 14 and the motor 16 and the battery 10 are not disposed,the handle portion 14 can be formed to be further thinned and can beformed in a state further easily gripped by the user.

The motor 16 is a DC motor with brush and disposed in the front portionof the main body housing 40.

The motor 16 includes a cylindrical motor case 90, a motor shaft 92 inthe front-rear direction, and a motor terminal 93. The motor shaft 92 isdisposed so as to penetrate the motor case 90 on its center axis and isrotatably driven around the center axis of itself. The motor terminal 93projects rearward from the rear portion of the motor case 90. The motor16 is electrically coupled to the controller 61 via the motor terminal93 with a lead wire (not illustrated).

The controller 61 controls driving of the motor 16 and controls therotation of the motor shaft 92 in the motor 16. When a current equal toor more than a predetermined threshold is detected, the controller 61grasps the unintended lock state of the motor shaft 92 and stops thedriving of the motor 16.

Additionally, the motor 16 includes a fan 94 integrally mounted with themotor shaft 92. The fan 94 is disposed inward a plurality of exhaustoutlets 95, which are circumferentially arranged in the motor case 90. Aplurality of exhaust outlets 96 are opened in parts positionedcircumferentially outward the exhaust outlets 95 in the main bodyhousing 40. It should be noted that the fan 94 may be disposedseparately from the motor 16 or may be omitted.

Meanwhile, a plurality of air inlets 98 are opened at the front and rearof the exhaust outlets 96 in the main body housing 40. The respectiveair inlets 98 are disposed at the front and rear of the motor 16. Apinion gear 99 is fixed to the distal end portion of the motor shaft 92integrally with the motor shaft 92.

The planetary gear mechanism 20 as a deceleration mechanism includes aring-shaped internal gear 100 having internal teeth, a plurality of(three) planetary gears 102 having external teeth meshing with theinternal gear 100, pins 104 as shafts for the respective planetary gears102, and a carrier 106 holding all (three) pins 104.

The internal gear 100 is unrotatably mounted into a reardiameter-expanded portion of the gear housing 42 via a gear retainer108. The gear retainer 108 extends from the inside of the reardiameter-expanded portion of the gear housing 42 to the inside of thefront end portion of the main body housing 40.

The planetary gears 102 are each disposed inward the internal gear 100.

Each pin 104 has a columnar shape having its front-rear direction in theaxis direction.

The respective planetary gears 102 are supported to the pins 104 in astate rotatable around the corresponding pin 104.

The carrier 106 is a ring-shaped member having a small-diameter portionon a front side of a large-diameter portion. The large-diameter portionof the carrier 106 has holes supporting the front portions of the pins104. The planetary gears 102 are disposed on the rear portions of therespective pins 104. The pins 104 and the planetary gears 102 arecircumferentially disposed at regular intervals. The pinion gear 99meshes with each planetary gear 102. The front end portion of the piniongear 99 enters the inside of the large-diameter portion of the carrier106. The carrier 106 is disposed rotatable around an axis of itself inthe front-rear direction inside a front diameter-expanded portion of thegear housing 42.

The spindle 22 as a reciprocating motion conversion mechanism is acolumnar member running along the front-rear direction and includes aspindle main body portion 110, a coupling portion 112, and a columnareccentric pin 116. The coupling portion 112 is concentric with thespindle main body portion 110 and projects rearward from a rear surfaceof the spindle main body portion 110 in a state where thecross-sectional surface has a non-rotation symmetrical shape (ovalshape) viewed at the center. The eccentric pin 116 projects forward fromthe front surface of the spindle main body portion 110 in an eccentricstate from the center axis of the spindle main body portion 110.

The spindle main body portion 110 is rotatably supported by front andrear bearings (needle bearings) 118 fixed inside the front portion ofthe gear housing 42 around the center axis in the front-rear direction.The center axis of the spindle main body portion 110, the center axis ofthe planetary gear mechanism 20, and the center axis of the motor shaft92 match, becoming the machine axis M of the electric ratchet wrench 1.

The coupling portion 112 enters an inner hole of the small-diameterportion of the carrier 106 having a cross-sectional shape identical tothe coupling portion 112 and is coupled so as to integrally rotate withthe carrier 106.

The eccentric pin 116 is covered with a barrel-shaped sleeve 120rotatable around the eccentric pin 116.

A light 122 is disposed under the spindle 22.

The light 122 is an LED and is entered in a depressed portion formed ina lower portion at the front end of the main body housing 40. A wiringgroove 124 to put a lead wire (not illustrated) of the light 122 isformed at the rear of the depressed portion in the main body housing 40.The light 122 is electrically coupled to the controller 61 via the leadwire.

The light 122 is disposed to face a front lower side to illuminatearound a lower side of the quadrilateral driving portion 34 c of thesocket adapter 34.

The holder 26 is a ring-shaped member made of metal having an innerdiameter slightly smaller than an inner diameter of the frame-shapedportion 52 of the gear housing 42 and disposed between an upper portionand a lower portion of the frame-shaped portion 52. The holder 26 isrotatably disposed around a center axis in the up-down direction of itsround hole. The holder 26 expands from front to back and from side toside, and the extended line of the machine axis M passes through acenter between top and bottom surfaces (thickness) of the holder 26 andis perpendicular to the center axis in the up-down direction of itsround hole. It should be noted that the machine axis M may be graspedincluding the holder 26 (output unit 32), and in this case, the machineaxis M is from the front end portion of the holder 26 to the rear endportion of the motor shaft 92.

The rear portion of the holder 26 reaches an inside of a front endportion of the handle-shaped portion 50 of the gear housing 42 andincludes a vertical groove 126 having a semi-cylindrical surface shapehaving an up-down direction in the axis direction.

The sleeve 120 and the eccentric pin 116 enter an inside of the verticalgroove 126, and right and left of the sleeve 120 contact the verticalgroove 126. The rotation of the spindle 22 rotates the eccentric pin 116and the sleeve 120 in the eccentric manner, and the movements of theportions in the right-left direction are transmitted to the holder 26via the vertical groove 126 by pressing the vertical groove 126 with thesleeve 120. Additionally, the movements of the portions in the up-downdirection are performed in the vertical groove 126 and are nottransmitted to the holder 26. The movements in the up-down direction aresmoothly performed by the rotation of the sleeve 120 around an eccentricpin 116. Thus, the rotation of the spindle 22 is converted intoreciprocating motions to the right and left, and the reciprocatingmotions are transmitted to the holder 26.

A tubular socket 28 is entered into the hole of the holder 26 and thehole of the frame-shaped portion 52 of the gear housing 42 overlappingwith the hole of the holder 26 via the one-way clutch mechanism 30.

In an inner hole in the up-down direction of the socket 28, 12 nutcorner contact grooves in which six corners of a hexagonal nut can beentered are formed extending up and down.

A direction switching lever 130 that switches the free direction and thelock direction of the one-way clutch mechanism 30 is disposed on thefront upper portion of the socket 28. It should be noted that thedirection switching lever 130 may be disposed in the holder 26.

The direction switching lever 130 includes a rod-shaped operating unit132 exposed on the top surface of the socket 28, a shaft portion 134that projects downward from one end part of the operating unit 132, anda cam portion 136 that projects from the lower end portion of the shaftportion 134 in a direction opposite to the operating unit 132. The shaftportion 134 is disposed at the center on the upper portion of the socket28. Depressed portions 138 are formed on right and left on the topsurface of the socket 28, and a projecting portion 139 (see FIG. 11)into which the depressed portion 138 can be entered is formed on thelower surface of the other end part of the operating unit 132. It shouldbe noted that the projecting portion 139 may be formed in the socket 28,the depressed portion 138 may be formed in the direction switching lever130, or a lock portion and a locked portion according to another aspectmay be formed.

When the operating unit 132 is disposed in a state where the projectingportion 139 enters one depressed portion 138, by an action of the camportion 136, the one-way clutch mechanism 30 allows the socket 28 torotate so as to relatively slide to the holder 26 in the predetermineddirection (free direction) and holds back the rotation of the socket 28to the holder 26 in the opposite direction (lock direction) tointegrally rotate the socket 28 and the holder 26. When the operatingunit 132 is operated from this state to a state where the projectingportion 139 enters the other depressed portion 138, the directionswitching lever 130 rotates around the shaft portion 134, the camportion 136 rotates and changes its posture, and the one-way clutchmechanism 30 switches the direction between the above-described freedirection and lock direction. It should be noted that even when theratchet mechanism using the gear and the claw is not used, since theelectric ratchet wrench 1 operates similarly to a wrench using theratchet mechanism as long as the free direction and the lock direction,which is the direction opposite to the free direction, are present likethe one-way clutch mechanism 30, the electric ratchet wrench 1 may bereferred to as a ratchet wrench.

The socket adapter 34 is mounted from the lower side of the socket 28.It should be noted that the user may insert a nut or the like into thesocket 28 in a state where the socket adapter 34 is not mounted and mayfasten the nut or the like.

The following further describes the one-way clutch mechanism 30 indetail.

FIG. 5 is a top view of the electric ratchet wrench 1, FIG. 6 is aperspective view of the one-way clutch mechanism 30 and the socket 28and the socket adapter 34, FIG. 7 and FIG. 8 are exploded perspectiveviews of FIG. 6, and the holder 26, the spindle 22 and the gear housing42, FIG. 9 is a cross-sectional view taken along the line A-A of FIG. 2,FIG. 10 is an enlarged view of a front right portion of FIG. 9, FIG. 11is a cross-sectional view taken along the line B-B of FIG. 5, FIG. 12 isa cross-sectional view taken along the line C-C of FIG. 3, and FIG. 13is an enlarged view of a front portion of FIG. 12.

The one-way clutch mechanism 30 includes a plurality of (eight) lockingpins 140, a retainer 142 and a ring 144 that hold the locking pins 140,an upper C-shaped ring 146 and a lower C-shaped ring 148 disposed aboveand below the retainer 142 and the ring 144, and the above-describeddirection switching lever 130.

The locking pins 140 as locking members each have a columnar shape andhas a size identical to one another. It should be noted that at leastone locking pin 140 may have a hollow columnar shape or a cylindricalshape.

The retainer 142 is a crown-shaped member and includes a ring-shapedbase portion 150 on the upper portion, eight projections 152 projectingdownward from the base portion 150, and springs 154 as elastic bodiesmounted to the respective projections 152.

Right and left pair of protrusions 156 projecting upward are formed onthe top surface at the front portion of the base portion 150. Aninstallation part of the direction switching lever 130 in a frontportion of a flange portion of the upper portion of the socket 28 isdepressed upward to be thin compared with another part of the flangeportion. The cam portion 136 of the direction switching lever 130 andthe protrusions 156 on the base portion 150 of the retainer 142 areentered into the depressed portion. The pair of protrusions 156 arepositioned right and left of the cam portion 136.

Additionally, these projections 152 are disposed at regular intervals ina circumferential direction. A surface outside in a radial direction ofeach projection 152 serves as a part of a cylindrical surface. Theprojections 152 each have a length in the up-down direction similar to alength of each locking pin 140.

The springs 154 include mounting portions wound outer sides in theradial direction at the centers of the projections 152 by half turn andleaf spring portions partially in contact with the projections 152 whilewarped into a “)” shape or a “(” shape on both sides of the mountingportions. It should be noted that the spring 154 may be an elasticblock, may be mounted by a method other than winding, or may beindividually disposed on each side of the projection 152.

The ring 144 contacts the lower end portions of the respectiveprojections 152 of the retainer 142 and is adjacent to the lower endportions of the respective locking pins 140.

The upper C-shaped ring 146 is interposed between the lower surface ofthe flange portion of the upper portion of the socket 28 and the topsurface of the base portion 150 to press the retainer 142 downward.

The lower C-shaped ring 148 is disposed on the lower side of the ring144 and is mounted to the lower portion of the frame-shaped portion 52of the gear housing 42 together with the ring 144.

The locking pins 140 in a state of having the up-down direction in itsaxis direction are disposed one by one between the adjacent projections152 and between the adjacent leaf spring portions of the springs 154.Each locking pin 140 has an upper end portion adjacent to the baseportion 150 of the retainer 142 and a lower end portion adjacent to thetop surface of the ring 144. Additionally, an inner surface of the holeof the holder 26 and an inner surface of the hole of the frame-shapedportion 52 of the gear housing 42 are positioned radially outward of thebase portion 150 in the respective locking pins 140. These innersurfaces are cylindrical surfaces. Meanwhile, the outer surface at thecenter of the socket 28 is positioned radially inward of the baseportion 150 in the respective locking pins 140. The outer surface at thecenter of the socket 28 has a shape equivalent to a side surface of aregular octagonal pillar. In more detail, the outer surface is a sidesurface of a chamfered regular octagonal pillar, that is, a side surfaceof a hexadecagonal pillar having a shape close to the regular octagonalpillar. Each side surface has a length in the up-down direction similarto a length of each locking pin 140. Additionally, each side surface hasa width in a circumferential direction around twice to three times of adiameter of each locking pin 140.

The pair of protrusions 156 are positioned on the upper side of the pairof projections 152 between which the locking pin 140 on the frontmost isinterposed, and the cam portion 136 of the direction switching lever 130is positioned above the locking pin 140 on the frontmost.

In a case where the operating unit 132 of the direction switching lever130 is engaged with the right depressed portion 138 (a case illustratedin each drawing), as illustrated in FIG. 13A, the cam portion 136 is ata rotation position (phase) where the most part of the cam portion 136is positioned left viewed from a rotational center T matching with thecenter of the shaft portion 134 to dispose the retainer 142 at a phaseillustrated in FIG. 10A via the protrusions 156. The respective lockingpins 140 are disposed at positions outward of one surface correspondingto the side surface of the socket 28 having the regular octagonal pillarand approaching a clockwise direction (a direction of an arrow L1) inFIG. 10A viewed from a center line U in the up-down direction passingthrough a circumferential center of the one surface with the projections152 of the retainer 142.

In this case, the spaces in which the respective locking pins 140 aredisposed include large interval portions and small interval portions.The large interval portion is interposed between a virtual firstsurface, which is formed by radially extending the center line U on theouter surface of the socket 28 to the inner surface of the hole of theholder 26 and the inner surface of the hole of the frame-shaped portion52, and a virtual second surface opposed to the first surface separatedaround a radius of the locking pin 140. The small interval portion isadjacent to the second surface of the large interval portion in thedirection of the arrow L1. A maximum distance Ka in a radial directionin the large interval portion is a dimension of a side in the radialdirection of the first surface and is larger than a smallest distance Kbin the radial direction in the small interval portion. The distance Kais equal to or more than the diameter of the locking pin 140, and thedistance Kb is less than the diameter of the locking pin 140.

In respective spaces in this case, the small interval portions are alldisposed in the direction of the arrow L1 viewed from the large intervalportions and are similar to one another in the rotation direction(circumferential direction) of the socket 28.

In this state, the rotation of the holder 26 in the direction of thearrow L1 (lock direction) causes the respective locking pins 140 toapproach the small interval portion sides from the state illustrated inthe drawing in association with the rotation of the holder 26 by, forexample, friction force and inertia force from the holder 26, and thelocking pins 140 are in line contact with the respective holder 26 andsocket 28 and are meshed between the portions, and the socket 28 locksthe holder 26 with the meshed locking pins 140 to rotate integrally withthe holder 26. The meshing of the locking pins 140 is assisted by thebiasing action caused by pressing by the leaf spring portions of thesprings 154 disposed on the side in the opposite direction to the arrowL1. It should be noted that the leaf spring portions of the springs 154disposed on the side of the arrow L1 direction are disposed so as tohardly act to the meshed locking pins 140 and therefore do not press themeshed locking pins 140.

Meanwhile, the rotation of the holder 26 in the direction opposite tothe arrow L1 (free direction) causes the respective locking pins 140 toapproach the large interval portion sides in association with therotation of the holder 26 as illustrated in the drawing to be releasedfrom the meshed state, the lock of the holder 26 by the socket 28 isreleased, the relative rotation of the socket 28 to the holder 26 isallowed, and the socket 28 idles to the holder 26.

Alternatively, in a case where the operating unit 132 of the directionswitching lever 130 is moved from a position engaged with the rightdepressed portion 138 to a position engaged with the left depressedportion 138, as illustrated in FIG. 13B, the cam portion 136 is rotatedto move to a phase where the most part of the cam portion 136 ispositioned right viewed from the rotational center T. Then, the retainer142 is rotated to move such that a distance becomes around one time to1.5 times of the diameter of each locking pin 140 (around a half of thewidth in the circumferential direction of each side surface of thesocket 28) to cause the retainer 142 to reach the phase illustrated inFIG. 10B. The respective locking pins 140 are disposed at positionsapproaching an anticlockwise direction (a direction of an arrow L2) inFIG. 10B viewed from the center line U on one side surface of the socket28 with the retainer 142.

In this case, the spaces in which the respective locking pins 140 aredisposed include large interval portions and small interval portions.The large interval portion is interposed between a virtual thirdsurface, which is formed by radially extending the center line U on theouter surface of the socket 28 to the inner surface of the hole of theholder 26 and the inner surface of the hole of the frame-shaped portion52, and a virtual fourth surface opposed to the third surface separatedaround a radius of the locking pin 140. The small interval portion isadjacent to the fourth surface of the large interval portion in thedirection of the arrow L2. A maximum distance Kc in a radial directionin the large interval portion is a dimension of a side in the radialdirection of the third surface and is larger than a smallest distance Kdin the radial direction in the small interval portion. The distance Kcis equal to or more than the diameter of the locking pin 140, and thedistance Kd is less than the diameter of the locking pin 140.

The distance Kc in this case is approximately identical to theabove-described distance Ka, and the large interval portion in this caseand the above-described large interval portion can be grasped as onecommon large interval portion.

Additionally, since the center of the socket 28 has the regularoctagonal pillar shape and the inner surface of the hole of the holder26 is the cylindrical surface, the small interval portion in this caseis symmetrical to the above-described small interval portion withrespect to the center line U as a symmetrical axis, and the distance Kdand the above-described distance Kb are approximately equal.

In respective spaces in this case, the small interval portions are alldisposed in the direction of the arrow L2 viewed from the large intervalportions and are similar to one another in the rotation direction(circumferential direction) of the socket 28.

In this state, the rotation of the holder 26 in the direction of thearrow L2 (lock direction) causes the respective locking pins 140 toapproach the small interval portion sides from the state illustrated inthe drawing, and the locking pins 140 are in line contact with therespective holder 26 and socket 28 and are meshed between the portions,and the socket 28 locks the holder 26 to rotate integrally with theholder 26. The meshing of the locking pins 140 is assisted by the biasby the leaf spring portions of the springs 154 disposed on the side inthe opposite direction to the arrow L2.

Meanwhile, the rotation of the holder 26 in the direction opposite tothe arrow L2 (free direction) causes the respective locking pins 140 toapproach the large interval portion sides as illustrated in the drawingto be released from the meshed state, the lock of the holder 26 by thesocket 28 is released, and the socket 28 idles to the holder 26.

The arrows L1 and L2, which correspond to the directions that the socket28 locks the holder 26, face the opposite directions to one another. Theuser changes the position of the operating unit 132 of the directionswitching lever 130 to ensure switching the lock direction. Thedirection of the arrow L2 is in the clockwise direction viewed fromabove and may be referred to as a forward direction, and the directionof the arrow L1 is in the anticlockwise direction viewed from the aboveand may be referred to as a reverse direction.

It should be noted that the numbers of locking pins and spaces are notlimited to eight but may be one or more to seven or less or may be nineor more. A part of the plurality of spaces and locking pins may havedifferent shapes and sizes from the other spaces and locking pins, thatis, the number of types of the spaces and the locking pins may beplural. In the spaces, the small interval portion may be disposed onlyon one side of the large interval portion. As long as the spaceincluding the large interval portion and the small interval portion isformed, the outer surface of the socket 28 may have a side surface shapeof another regular polygonal prism or may have a side surface shape of apolygonal prism, such as an octagonal pillar not a regular octagonalpillar. Additionally, the outer surface of the socket 28 may beconfigured to have a cylindrical surface shape (columnar surface shape),the inner surface of the hole of the holder 26 may be configured to havea side surface shape of a regular polygonal prism or a side surfaceshape of a polygonal prism not a regular polygonal prism, or both of theouter surface of the socket 28 and the inner surface of the hole of theholder 26 may be configured to have a side surface shape of a polygonalprism. Alternatively, for example, a curved surface, such as an ellipticcylindrical surface, and a combination of a curved surface and a sidesurface of a polygonal prism may be used.

The operation example of the electric ratchet wrench 1 will bedescribed.

The user mounts the battery 10 preliminarily charged with a charger tothe battery mounting portion 12 by sliding forward.

Then, when the user grips the handle portion 14, slides the slider 78 onthe lock arm 76 rearward, and presses the button portion 72 on the lever68 upward, the plunger 66 is pressed upward and the switch 62 switchesto on. The battery 10 feeds power to the light 122 and the motor 16 viathe controller 61, the light 122 lights up to illuminate below thesocket 28, and the motor shaft 92 of the motor 16 is driven by thecontrol by the controller 61. It should be noted that the switching ofthe switch 62 and the control by the controller 61 may be adjusted suchthat switching timings of the light 122 and the motor 16 becomedifferent, such as the light 122 turning on at the beginning of a risingof the plunger 66 (beginning of pressing the button portion 72) and themotor 16 tuning on at further rising (pressing the button portion 72).

The rotation of the motor shaft 92 rotates the fan 94 to exhaust airfrom the exhaust outlets 95 and 96 and wind from the air inlets 98 tothe exhaust outlets 95 and 96 is formed. The wind cools an internalmechanism of the electric ratchet wrench 1, such as the motor 16.

Further, a rotation force of the motor shaft 92 is decelerated by theplanetary gear mechanism 20 and transmitted to the spindle 22. Therotation force of the spindle 22 is converted into the right and leftreciprocating rotation motion forces of the holder 26, and the convertedforces are appropriately transmitted to the socket 28 via the one-wayclutch mechanism 30.

The action of the one-way clutch mechanism 30 applies the reciprocatingrotation motion force in the lock direction to the socket 28 and thesocket adapter 34 and the exchange socket mounted to the socket 28 bythe meshing of the respective locking pins 140 in the small intervalportions. The reciprocating rotation motion force in the free directionis not applied by releasing the meshing by the movement of therespective locking pins 140 to the large interval portions. Accordingly,the socket 28 and the exchange socket give a torque to the fitted nut orthe like only in the lock direction and do not give a torque in theopposite direction. Therefore, the fastening of the nut or the like isprogressed intermittently in the lock direction at each reciprocationmotion or the removal is similarly progressed.

In a case where an electric power of the battery 10 becomesinsufficient, the user removes the battery 10 from the battery mountingportion 12 by sliding rearward, sets the battery 10 to the charger forcharging, and mounts the charged battery 10 or another battery 10 to thebattery mounting portion 12.

The electric ratchet wrench 1 according to the first embodimentdescribed above includes the electric motor 16, the holder 26, and thespindle 22. The holder 26 rotatably holds the socket 28 via the one-wayclutch mechanism 30. The spindle 22 is configured to convert the drivingforce from the motor 16 into the reciprocating rotation motion of theholder 26. The space is provided between the socket 28 and the holder26. The space includes the large interval portion and the small intervalportion. The small interval portion is adjacent to the large intervalportion in the rotation direction (lock direction) of the socket 28. Thesmall interval portion has the distance Kb or Kd smaller than that(distance Ka or Kc) of the large interval portion. The one-way clutchmechanism 30 includes the columnar locking pin 140 disposed in thespace. The locking pin 140 has the diameter having the size equal to orless than the distance Ka or Kc of the large interval portion andexceeding the distance Kb or Kd of the small interval portion.

Accordingly, the rotation of the holder 26 in the direction from thelarge interval portions to the small interval portions (lock direction)causes the locking pins 140 to enter the small interval portions havingthe distances Kb and Kd less than the diameter of the locking pin 140and to be meshed between the holder 26 and the socket 28, and the socket28 integrally rotates with the holder 26. Meanwhile, the rotation of theholder 26 in the direction from the small interval portions to the largeinterval portions (free direction) causes the locking pins 140 to enterthe large interval portions having the distances Ka and Kc equal to ormore than the diameter of the locking pin 140, the meshing of thelocking pins 140 between the holder 26 and the socket 28 is released,and the socket 28 idles to the holder 26.

The one-way clutch mechanism 30 includes the large interval portions andthe small interval portions, and can be installed only by ensuring thespaces where the locking pins 140 are entered, which results in beingcompact. Further, since the one-way clutch mechanism 30 performs lockingby meshing the locking pins 140, sufficient locking strength can beobtained without increasing the sizes of the locking pins 140 so much.Therefore, the electric ratchet wrench 1 having both compactability anda lock performance is provided.

Additionally, the small interval portions are disposed on both sides inthe circumferential direction of the large interval portions. Theretainer 142 that can change the spaces for one small interval portionand large interval portion (see FIG. 10A) to spaces for another smallinterval portion and large interval portion (see FIG. 10B) is disposedbetween the socket 28 and the holder 26. Accordingly, the retainer 142can switch the direction that the locking pins 140 are meshed from thelarge interval portions to the small interval portions. Thus, the lockdirection can be easily and reliably switched.

Further, the retainer 142 includes the pair of protrusions 156, and thedirection switching lever 130 including the cam portion 136 in contactwith the protrusions 156 is disposed on the socket 28. Accordingly, thelock direction can be further easily and reliably switched.

Further, the springs 154 that bias the locking pins 140 in the directionwhere the small interval portions are disposed viewed from the largeinterval portions are disposed in the retainer 142. Accordingly, themovement of the locking pins 140 to the small interval portions isassisted, and the socket 28 is further smoothly locked with the lockingpins 140, thus further improving the lock performance.

In addition, the plurality of spaces are disposed in the state where thearrangements of the small interval portions relative to the largeinterval portions in the rotation direction are similar to one another,and the locking pins 140 are disposed between the respective spaces.Accordingly, the plurality of locking pins 140 mesh in the lockdirection, and thus the electric ratchet wrench 1 with the furtherimproved locking strength is provided.

Additionally, the socket 28 has the outer surface formed into the sidesurface shape of the regular octagonal pillar, and the holder 26 has theinner surface formed into the cylindrical surface shape. Accordingly,the spaces including the large interval portions and the small intervalportions are simply formed, and the plurality of spaces including thesmall interval portions on both sides of the large interval portions aresimply formed.

It should be noted that the above-described electric ratchet wrench 1 asone example of the straight type electric power tool includes the motor16, the power transmission unit 24, the battery 10, and the batterymounting portion 12. The power transmission unit 24 transmits thedriving force from the motor 16 to the output unit 32 on the front side.The battery 10 drives the motor 16. The battery 10 is mounted to thebattery mounting portion 12. The motor 16, the power transmission unit24, and the output unit 32 are linearly arranged in the front-reardirection. The output axis O of the output unit 32 is directed in theup-down direction intersecting with the front-rear direction and extendsdownward. The battery mounting portion 12 is disposed at the rear of thepower transmission unit 24 and the motor 16. The battery 10 is slidinglymounted to the upper side (the side opposite to the side from which theoutput axis O extends) of the battery mounting portion 12. Thus, thebattery 10 is easily replaced and the electric ratchet wrench 1excellent in operability regarding the battery 10 is provided.

Additionally, the battery 10 is mounted so as to be oriented in thefront-rear direction. Accordingly, the mounted battery 10 is oriented inthe same direction as the direction in which the motor 16, the powertransmission unit 24, and the output unit 32 are arranged. The battery10 is mounted with a small protrusion from the motor 16, the powertransmission unit 24, and the output unit 32, thereby furtherfacilitating the operation of the electric ratchet wrench 1.

Further, the motor 16, the power transmission unit 24, and the outputunit 32 are arranged around the machine axis M, and the battery mountingportion 12 is put to one side, which is the lower side, with respect tothe machine axis M. Thus, compared with a case where the batterymounting portion 12 is not put to one side, the battery 10 is mountedmore closer to the machine axis M. Accordingly, the battery 10 ismounted with a further small protrusion and its center of gravity isfurther close to the machine axis M, thus improving the operability ofthe electric ratchet wrench 1.

It should be noted that the first embodiment of the invention is notlimited to the above-described embodiments and modification examplesbut, for example, further includes the following modification examplesappropriately.

The battery mounting portion may be formed to face downward such thatthe terminal projects downward from the lower surface and further may beput to one side, which is the upper side, with respect to the machineaxis or its extended line.

A plurality of batteries may be mounted. In this case, when allbatteries are disposed to be oriented in the front-rear direction, thebatteries are each mounted with a small protrusion. For example, therespective batteries oriented in the front-rear direction may be mountedto the top and bottom of the rear portion of the main body housingformed so as to expand from front to back and from side to sideincluding the machine axis or its extended line.

The batteries may be mounted to the right and left of the rear portionof the main body housing. Additionally, the battery may be mounted in anoblique direction having an angle with respect to a direction(front-rear direction) in which the motor, the planetary gear mechanism,and the spindle are arranged. Further, the battery mounting portion maybe rotatable to another part, such as the main body housing, such that aposture of the mounted battery (for example, from a horizontal postureto a vertical posture) relative to the front-rear direction becomesvariable.

Regarding the planetary gear mechanism, instead of the insertion of thepin to the carrier, for example, a shaft-shaped protrusion may be formedintegrally with the carrier.

The planetary gear mechanism may be changed to another decelerationmechanism, may be configured as a mechanism transmitting power withoutdeceleration, or may be omitted.

One or two or more of intermediate shafts may be interposed between themotor shaft and the holder.

As the battery, any lithium-ion battery, such as 14.4 V, 18 V (maximum20 V), 18 V, 25.2 V, 28 V, and 36 V may be used, a lithium-ion batteryhaving a voltage less than 10.8 V or exceeding 36 V may be used, or abattery of another type may be used. The battery may be rechargeable ina state being mounted to the battery mounting portion.

Instead of the battery mounting portion and the battery, a power supplycord coupled to a commercial power supply may be disposed and an ACmotor is used as the motor to configure an AC electric ratchet wrench.Alternatively, the motor may be configured as a motor driven by air toconfigure an air ratchet wrench as one example of an air tool. With theair ratchet wrench, the spindle may be directly rotated by air. Thenumbers of various members and parts, and arrangements, materials,sizes, configurations, and the like of various members and parts may beappropriately changed, such as increase and decrease in the number ofsections of the housing, the number of installed planetary gears, thenumber of stages of the planetary gear mechanism, the number of exhaustoutlets, and the number of bearings.

Further, the invention is applicable to, for example, another straighttype electric power tool, such as a multi tool and a multi cutter, astraight type electric power tool coupled to a commercial power supply,or a straight type gardening tool, such as a trimmer for gardening.

Second Embodiment

An electric ratchet wrench according to the second embodiment of theinvention is configured similarly to the first embodiment excluding thelocking pins and the retainer of the one-way clutch mechanism and thesocket. Same reference numerals are given to the members and the partsconfigured similarly to those of the first embodiment and descriptionsthereof are appropriately omitted.

FIG. 14 is a drawing according to the second embodiment similar to FIG.10.

An outer surface at the center of a socket 228 of the second embodimenthas a shape equivalent to a side surface of a regular nonagonal pillar.

Locking pins 240 of a one-way clutch mechanism 230 of the secondembodiment are disposed by nine. Projections 252 of a retainer 242 ofthe second embodiment are disposed by nine, and nine spaces are disposedbetween the projections 252 where the locking pins 240 are disposedsimilarly to the first embodiment.

The respective locking pins 240 as locking members are pillar-shapedmembers having the axis direction in the up-down direction. Across-sectional surface of each locking pin 240 perpendicular to theaxis direction has an elliptical shape. In more detail, thecross-sectional surface has a shape enclosed by a pair of parallelstraight lines facing one another and a pair of arcs convexed outwardcoupled to any one of end portions of the straight lines. Accordingly,the locking pins 240 each include a pair of planar portions 240 aparallel in the axis direction and a pair of cylindrical surface-shapedbulge portions 240 b.

In each locking pin 240, a virtual plane parallel to both planarportions 240 a at equal distances includes a center axis at the centerof the socket 228. Each locking pin 240 faces a radial direction as adirection perpendicular to the rotation direction of the socket 228 (adirection perpendicular to the retainer 242 and the annular-shaped partof the holder 26). Between the pair of bulge portions 240 b (distanceJ1) has a size equal to or less than the distances Ka and Kc of thelarge interval portions and exceeding the distances Kb and Kd of thesmall interval portions in the spaces in which the respective lockingpins 240 are disposed.

Each locking pin 240 has a locking pin side depressed portion 240 c,which depresses inward, at the center in the up-down direction in eachplanar portion 240 a.

Additionally, projection part side depressed portions 252 a, whichdepress inward, are disposed on both sides of the projection 252 of theretainer 242 in a circumferential direction and parts opposed to thelocking pin side depressed portions 240 c.

Springs 254 instead of the springs 154 of the first embodiment arebridged between the locking pin side depressed portions 240 c and theprojection part side depressed portions 252 a facing one another.

The electric ratchet wrench of the second embodiment operates similarlyto the electric ratchet wrench 1 of the first embodiment.

Especially, with an action of the one-way clutch mechanism 230, thereciprocating rotation motion force in the lock direction is applied tothe socket 228 and the socket adapter 34 and the exchange socket mountedto the socket 228 by the pair of bulge portions 240 b (distance J1) ofthe respective locking pins 240 being meshed to the small intervalportions in line contact. The reciprocating rotation motion force in thefree direction is not applied by releasing the meshing by the movementof the respective locking pins 240 to the large interval portions.

The meshing of the respective locking pins 240 are assisted by thebiasing action by the springs 254 disposed on both sides of theprojection 252 in the circumferential direction.

The electric ratchet wrench of the second embodiment includes theelectric motor 16, the holder 26, and the spindle 22. The holder 26rotatably holds the socket 228 via the one-way clutch mechanism 230. Thespindle 22 is configured to convert the driving force from the motor 16into the reciprocating rotation motion of the holder 26. The space isprovided between the socket 228 and the holder 26. The space includesthe large interval portion and the small interval portion. The smallinterval portion is adjacent to the large interval portion in therotation direction (lock direction) of the socket 228. The smallinterval portion has the distance Kb or Kd smaller than that (distanceKa or Kc) of the large interval portion. The one-way clutch mechanism230 includes the locking pin 240 disposed in the space. The locking pin240 has the size equal to or less than the distance Ka or Kc of thelarge interval portion and exceeding the distance Kb or Kd of the smallinterval portion (distance J1).

Accordingly, the rotation of the holder 26 in the direction from thelarge interval portions to the small interval portions (lock direction)causes the locking pins 240 to enter the small interval portions havingthe distances Kb and Kd less than the size between the bulge portions240 b (distance J1) and to be meshed between the holder 26 and thesocket 228, and the socket 228 integrally rotates with the holder 26.Meanwhile, the rotation of the holder 26 in the direction from the smallinterval portions to the large interval portions (free direction) causesthe locking pins 240 to enter the large interval portions having thedistances Ka and Kc equal to or more than the size between the bulgeportions 240 b (distance J1), the meshing of the locking pins 240between the holder 26 and the socket 228 is released, and the socket 228idles to the holder 26.

The one-way clutch mechanism 230 includes the large interval portionsand the small interval portions, and can be installed only by ensuringthe spaces where the locking pins 240 are entered, which results inbeing compact. Further, since the one-way clutch mechanism 230 performslocking by meshing the locking pins 240, sufficient locking strength canbe obtained without increasing the sizes of the locking pins 240 somuch. Therefore, the electric ratchet wrench having both compactabilityand a lock performance is provided.

Additionally, the locking pin 240 includes the pair of planar portions240 a, which are arranged in the direction that the small intervalportions are disposed viewed from the large interval portions(circumferential direction), and the pair of bulge portions 240 b, whichcouple between the end portions of the planar portions 240 a. The sizebetween the pair of bulge portions 240 b (distance J1) is equal to orless than the distances Ka and Kc of the large interval portions andexceeding the distances Kb and Kd of the small interval portions.Accordingly, while the locking with the sufficient strength is obtainedwith the bulge portions 240 b, the planar portions 240 a make thelocking pins 240 and eventually the holder 26 and the socket 228compact. Additionally, disposing the locking pin side depressed portions240 c in the planar portions 240 a prevents each locking pin 240 fromrolling in the space and the springs 254 reliably enter the locking pinside depressed portions 240 c. Even if the spring 254, which assists themeshing of each locking pin 240, has a shape other than the leaf springor a comparatively large size, the spring 254 is reliably held.

Further, the pair of planar portions 240 a are parallel to one another.Thus, the locking pin 240 or the like is downsized, and the holdingportion where the spring 254 is reliably held is simply installed.

The electric ratchet wrench of the second embodiment appropriately hasthe modification examples similar to those of the first embodiment.

Additionally, at least one of the bulge portions 240 b needs not to havethe cylindrical surface.

The number of locking pins 240 may be a number other than nine. Thesocket 228 may have an octagonal pillar shape or less or may have adecagonal pillar shape or more, or may have another shape.

The locking pins 140 and 240 of the first and the second embodiments maybe mixed.

Third Embodiment

An electric ratchet wrench according to the third embodiment of theinvention is configured similarly to the second embodiment excluding thelocking pins and the retainer of the one-way clutch mechanism. Samereference numerals are given to the members and the parts configuredsimilarly to those of the second embodiment and descriptions thereof areappropriately omitted.

FIG. 15 is a drawing according to the third embodiment similar to FIG.10.

In a projection 352 of a retainer 342 in a one-way clutch mechanism 330of the third embodiment, an arc radially outside in its cross-sectionalsurface has a shape longer than an inner arc and surfaces of both endportions in the circumferential direction have a posture of expandingfrom a radial direction toward radially inside. In surfaces of both endportions in the circumferential direction of the projection 352,projection portion side depressed portions 352 a perpendicular to theprojection 352 are disposed.

The pair of planar portions 340 a in nine locking pins 340 have aposture of expanding toward the socket 228. The planar portion 340 afaces the surface of the end portion in the circumferential direction ofthe projection 352 parallel to one another. The planar portions 340 aeach include a locking pin side depressed portion 340 c perpendicular tothe planar portion 340 a. The locking pin side depressed portion 340 cfaces the projection portion side depressed portion 352 a. The size(distance J2) between bulge portions 340 b, which couple between the endportions of the respective planar portions 340 a, is equal to or lessthan the distances Ka and Kc of the large interval portions andexceeding the distances Kb and Kd of the small interval portions in thespaces in which the locking pins 340 are disposed.

The spring 254 similar to those of the second embodiment is bridgedbetween the locking pin side depressed portion 340 c and the projectionportion side depressed portion 352 a, which faces one another, so as tobe oriented in the same directions of the locking pin side depressedportion 340 c and the projection portion side depressed portion 352 a.

The electric ratchet wrench of the third embodiment operates similarlyto the electric ratchet wrench of the second embodiment.

Especially, with the action of the one-way clutch mechanism 330, thereciprocating rotation motion force in the lock direction is applied tothe socket 228 and the socket adapter 34 and the exchange socket mountedto the socket 228 by the pair of bulge portions 340 b (distance J2) ofthe respective locking pins 340 being meshed to the small intervalportions in line contact. The reciprocating rotation motion force in thefree direction is not applied by releasing the meshing by the movementof the respective locking pins 340 to the large interval portions.

The meshing of the respective locking pins 340 are assisted by thebiasing action by the springs 254 disposed on both sides of theprojection 352 in the circumferential direction.

The one-way clutch mechanism 330 of the electric ratchet wrenchaccording to the third embodiment includes the locking pin 340 disposedin the space. The locking pin 340 has the size equal to or less than thedistance Ka or Kc of the large interval portion and exceeding thedistance Kb or Kd of the small interval portion (distance J2).

Accordingly, the rotation of the holder 26 in the direction from thelarge interval portions to the small interval portions (lock direction)causes the locking pins 340 to enter the small interval portions havingthe distances Kb and Kd less than the size between the bulge portions340 b (distance J2) and to be meshed between the holder 26 and thesocket 228, and the socket 228 integrally rotates with the holder 26.Meanwhile, the rotation of the holder 26 in the direction from the smallinterval portions to the large interval portions (free direction) causesthe locking pins 340 to enter the large interval portions having thedistances Ka and Kc equal to or more than the size between the bulgeportions 340 b (distance J2), the meshing of the locking pins 340between the holder 26 and the socket 228 is released, and the socket 228idles to the holder 26.

The one-way clutch mechanism 330 includes the large interval portionsand the small interval portions, and can be installed only by ensuringthe spaces where the locking pins 340 are entered, which results inbeing compact. Further, since the one-way clutch mechanism 330 performslocking by meshing the locking pins 340, sufficient locking strength canbe obtained without increasing the sizes of the locking pins 340 somuch. Therefore, the electric ratchet wrench having both compactabilityand a lock performance is provided.

Additionally, the locking pin 340 includes the pair of planar portions340 a, which are arranged in the direction that the small intervalportions are disposed viewed from the large interval portions(circumferential direction), and the pair of bulge portions 340 b, whichcouple between the end portions of the planar portions 340 a. The sizebetween the pair of bulge portions 340 b (distance J2) is equal to orless than the distances Ka and Kc of the large interval portions andexceeding the distances Kb and Kd of the small interval portions.Accordingly, while the locking with the sufficient strength is obtainedwith the bulge portions 340 b, the planar portions 340 a make thelocking pins 340 and eventually the holder 26 and the socket 228compact. Additionally, disposing the locking pin side depressed portions340 c in the planar portions 340 a prevents each locking pin 340 fromrolling in the space and the springs 254 reliably enter the locking pinside depressed portions 340 c. Even if the spring 254, which assists themeshing of each locking pin 340, has a shape other than the leaf springor a comparatively large size, the spring 254 is reliably held.

Further, the pair of planar portions 340 a have a posture of expandingtoward the socket 228. Accordingly, the locking pin 340 is each disposedin a state so as to increase in size in the circumferential direction asheading radially inward between the projections 352 of the retainer 342.Accordingly, when the holder 26, the socket 228, and the one-way clutchmechanism 330 are manufactured, the respective locking pins 340 are lesslikely to come off outside.

The electric ratchet wrench of the third embodiment appropriately hasthe modification examples similar to those of the second embodiment.

Additionally, at least one planar portion 340 a may be configured as acurved surface and have a posture of expanding toward the socket 228.

At least any of two kinds of the locking pins 140, 240, and 340according to the first to the third embodiment may be mixed.

Fourth Embodiment

An electric ratchet wrench according to the fourth embodiment of theinvention is configured similarly to the first embodiment excluding thelocking pins and the retainer of the one-way clutch mechanism. Samereference numerals are given to the members and the parts configuredsimilarly to those of the first embodiment and descriptions thereof areappropriately omitted.

FIGS. 16A and 16B are exploded perspective views of a retainer and ballsof the electric ratchet wrench according to the fourth embodiment whenviewed from a left upper side (FIG. 16A) and a left lower side (FIG.16B).

In a retainer 442 in the one-way clutch mechanism of the fourthembodiment, the projections 152 of the first embodiment are disposed bynine and lower end portions of the respective projections 152 arecoupled into a ring shape (the ring 144 is integrated with the retainer142.) That is, the retainer 442 is a cylindrical member having ninewindows 442 a circumferentially arranged and each extending up and down.Thus, since the retainer 442 is configured by coupling the lower endportions of the respective projections 152 into the ring shape, thestrength is further excellent.

Excluding that leaf spring portions are not warped and mounting portionsof leaf springs are routed to an inside of the retainer 442, springs 454configured similarly to the springs 154 of the first embodiment aredisposed on both sides of the windows 442 a in the circumferentialdirection.

Since the nine windows 442 a are disposed, the nonagonal pillar-shapedsocket 228 according to the second embodiment is used in the fourthembodiment.

Similar to the space between the projections 152 of the retainer 142 ofthe first embodiment, the respective windows 442 a form spaces includingthe large interval portions (distances Ka and Kc) and the small intervalportions (distances Kb and Kd) between the socket 228 and the holder 26.

In each window 442 a, three balls 440 (locking members) made of iron aredisposed to be arranged up to down.

Each ball 440 has a diameter with a size (distance J3) equal to or lessthan the distance Ka or Kc of the large interval portion and exceedingthe distance Kb or Kd of the small interval portion.

The balls 440 are each configured to contact the spring 454.

The electric ratchet wrench of the fourth embodiment operates similarlyto the electric ratchet wrench 1 of the first embodiment.

Especially, with an action of the one-way clutch mechanism of the fourthembodiment, the reciprocating rotation motion force in the lockdirection is applied to the socket 228 and the socket adapter 34 and theexchange socket mounted to the socket 228 by meshing (point contact) ofeach ball 440 (of which diameter is distance J3) to the small intervalportion. The reciprocating rotation motion force in the free directionis not applied by releasing the meshing by the movement of therespective balls 440 to the large interval portions.

The meshing of the respective balls 440 is assisted by a biasing actionof the springs 454 disposed on both sides of the windows 442 a in thecircumferential direction.

The one-way clutch mechanism of the electric ratchet wrench of thefourth embodiment includes the balls 440 disposed in the windows 442 aand having the size (distance J3) equal to or less than the distances Kaand Kc of the large interval portions and exceeding the distances Kb andKd of the small interval portions.

Accordingly, the rotation of the holder 26 in the direction from thelarge interval portions to the small interval portions (lock direction)causes the balls 440 to enter the small interval portions having thedistances Kb and Kd less than the diameter of the balls 440 (distanceJ3) and to be meshed between the holder 26 and the socket 228, and thesocket 228 integrally rotates with the holder 26. Meanwhile, therotation of the holder 26 in the direction from the small intervalportions to the large interval portions (free direction) causes theballs 440 to enter the large interval portions having the distances Kaand Kc equal to or more than the size of the diameter of the ball 440(distance J3), the meshing of the balls 440 between the holder 26 andthe socket 228 is released, and the socket 228 idles to the holder 26.

The one-way clutch mechanism of the fourth embodiment includes the largeinterval portion and the small interval portion, and can be installedonly by ensuring the spaces where the balls 440 are entered, whichresults in being compact. Further, since the one-way clutch mechanism ofthe fourth embodiment performs locking by meshing the balls 440,sufficient locking strength can be obtained without increasing the sizesof the balls 440 so much.

Therefore, the electric ratchet wrench having both compactability and alock performance is provided.

Additionally, since the locking members are the balls 440, the lockingmember can be achieved at a low cost.

The electric ratchet wrench according to the fourth embodimentappropriately has modification examples similar to those of the first tothird embodiments.

Additionally, the balls 440 may be disposed in each window 442 a by twoor less or may be disposed by four or more, or the different numbers ofthe balls 440 may be disposed in each of the windows 442 a.

A locking member formed by coupling the plurality of balls 440 into arod shape may be employed.

The number of windows 442 a may be eight or less or may be 10 or more.Arrangement of the windows 442 a may be changed, such as the pluralityof windows 442 a being arranged in the up-down direction.

At least any of two kinds of the locking pins 140, 240, and 340, and theballs 440 of the first to fourth embodiment may be mixed.

In the first to third embodiments, the retainer 442 according to thefourth embodiment may be used.

The invention claimed is:
 1. An electric wrench comprising: an electricmotor; a holder configured to rotatably hold a tool bit or a tool bitholder via a one-way clutch mechanism; a reciprocating motion conversionmechanism configured to convert a driving force from the motor into areciprocating rotation motion of the holder; a body housing that housesthe electric motor; a gear housing that (1) houses the holder and adeceleration mechanism configured to decelerate the holder and (2) isconnected to the body housing; and a light configured to illuminate thetool bit or the tool bit holder; wherein: a space is between (1) thetool bit or the tool bit holder and (2) the holder; the space includeslarge interval portions and small interval portions, the small intervalportions being adjacent to the large interval portions in a rotationdirection of the tool bit or the tool bit holder, the small intervalportions having radial distances smaller than radial distances of thelarge interval portions; the one-way clutch mechanism includes lockingmembers in the space, each of the locking members having a size equal toor less than the radial distances of the large interval portions andexceeding the radial distances of the small interval portions; the gearhousing has a small diameter portion and a large diameter portion; thesmall diameter portion has a smaller diameter than the large diameterportion in planes perpendicular to a longitudinal axis of the electricwrench; the large diameter portion is rearward of the small diameterportion along the longitudinal axis; a rear portion of the smalldiameter portion is connected to the body housing; the large diameterportion overlaps the body housing in the planes perpendicular to thelongitudinal axis; and the light is (1) held by the body housing and (2)under the small diameter portion.
 2. The electric wrench according toclaim 1, wherein the each of the locking members includes a pair ofplanar portions and a pair of bulge portions, the pair of planarportions being arranged in a direction that the small interval portionsare disposed viewed from the large interval portions, the pair of bulgeportions coupling between end portions of the planar portions, and asize between the pair of bulge portions is equal to or less than theradial distances of the large interval portions and exceeding the radialdistances of the small interval portions.
 3. The electric wrenchaccording to claim 2, wherein the pair of the planar portions areparallel.
 4. The electric wrench according to claim 2, wherein the pairof planar portions have a posture of expanding toward the tool bit orthe tool bit holder.
 5. The electric wrench according to claim 1,wherein the locking member is at least one ball.
 6. The electric wrenchaccording to claim 1, wherein the small interval portions are on bothsides of each of the large interval portions, and a retainer is between(1) the tool bit or the tool bit holder and (2) the holder, the retainerbeing configured to change the spaces of one small interval portion andone interval portion to the spaces of another small interval portion andanother large interval portion.
 7. The electric wrench according toclaim 6, wherein the retainer includes a protrusion, and a directionswitching lever including a cam portion in contact with the protrusionis on one of (1) the holder and (2) the tool bit or the tool bit holder.8. The electric wrench according to claim 6, wherein springs that biasthe locking members in a direction, where the small interval portionsare disposed viewed from the large interval portions, are in theretainer.
 9. The ratchet wrench according to claim 1, wherein the toolbit or the tool bit holder has an outer surface of a side surface shapeof a regular polygonal prism, and the holder has an inner surface of acylindrical shape.
 10. An electric wrench comprising: an electric motor;a holder configured to rotatably hold a tool bit or a tool bit holdervia a one-way clutch mechanism; a reciprocating motion conversionmechanism configured to convert a driving force from the motor into areciprocating rotation motion of the holder; a body housing that housesthe electric motor; a gear housing that (1) houses the holder and adeceleration mechanism configured to decelerate the holder and (2) isconnected to the body housing; and a light configured to illuminate thetool bit or the tool bit holder; wherein: a space is between (1) thetool bit or the tool bit holder and (2) the holder; the space includeslarge interval portions and small interval portions, the small intervalportions being adjacent to the large interval portions in a rotationdirection of the tool bit or the tool bit holder, the small intervalportions having radial distances smaller than radial distances of thelarge interval portions; and the one-way clutch mechanism includescolumnar or cylindrical locking members in the space, each of thelocking members having a diameter equal to or less than the radialdistances of the large interval portions and exceeding the radialdistances of the small interval portions.
 11. An electric wrenchcomprising: an electric motor; a deceleration mechanism coupled to theelectric motor; a spindle coupled to the deceleration mechanism; aholder configured to rotatably hold a tool bit or a tool bit holder viaa one-way clutch mechanism; a reciprocating motion conversion mechanismconfigured to convert a rotating motion of the spindle into areciprocating rotation motion of the holder; a body housing that housesthe electric motor and is configured to receive and retain a removablebattery pack; a gear housing that (1) houses the reciprocating motionconversion mechanism, the holder and the spindle, (2) has a smalldiameter portion covering the spindle and a large diameter portioncovering the deceleration mechanism and (3) is partially covered by thebody housing; and a light below the small diameter portion and supportedby the body housing, the light configured to illuminate the tool bit orthe tool bit holder, wherein the electric motor is in front of thebattery pack, the deceleration mechanism is in front of the electricmotor, the spindle is in front of the deceleration mechanism, and theholder is in front of the spindle.
 12. The electric wrench according toclaim 11, further comprising a bearing between the spindle and the smalldiameter portion, wherein the light is below the bearing.
 13. Theelectric wrench according to claim 11, wherein the body housing has ascrew boss portion between the light and the deceleration mechanism in afront-rear direction.